In many portable, battery-powered applications, power consumption is very important. Examples of such applications include, but are not limited to, cellular phones, pagers, camera recorders and laptops. These applications demand the lowest power consumption possible in order to prolong battery life and to enable the use of smaller, lower capacity batteries to reduce the application size, cost, and weight. Many of these applications use flash memory devices to store program code and, in some instances, the program code is copied into external or embedded microcontroller random access memory (RAM) after the application powers up. Since the code is shadowed from the flash memory into RAM, the flash memory does not need to be accessed until the next power cycle. In these instances, it can be desirable to put the flash memory device into as low a power mode as possible so as to consume the least amount of current.
Some applications completely remove power from the flash memory device to reduce the power consumption. However, doing so tends to increase the application complexity, as well as the cost, because an external power management device such as a low drop-out (LDO) regulator must be used to cut the power to the flash memory device.